Artificial leather for automotive interior materials and method of manufacturing the same

ABSTRACT

The present invention relates to an artificial leather for automotive interior materials and a method of manufacturing the same. More specifically, the artificial leather of the present invention has a seam line formed thereon, and is used in a covering process of automotive interior materials. According to the present invention, the artificial leather of the present invention is wrinkle-free, allows easy deployment of an airbag, and has excellent durability.

TECHNICAL FIELD

The present invention relates to an artificial leather for automotive interior materials and a method of manufacturing the same. More specifically, the artificial leather of the present invention has a seam line formed thereon, and is used in a covering process of automotive interior materials. According to the present invention, the artificial leather of the present invention is wrinkle-free, allows easy deployment of an airbag, and has excellent durability.

Background Art

Automotive interior materials such as crash pads, door trims, console boxes, armrests, headrests, and head liners are typically composed of a skin layer, a foam layer, and a core layer, which is a hard synthetic resin injection product. In this case, the skin layer, the foam layer, and the core layer are laminated in order from top to bottom.

Automotive interior materials may be manufactured by various methods. For example, after forming a skin layer by vacuum forming a sheet for automotive interior materials including an outermost layer and a foam layer formed on the bottom of the outermost layer, the skin layer is mounted in a mold, and a synthetic resin is injected to form a core layer under the skin layer, thereby manufacturing an integrated automotive interior material.

In recent years, to impart a luxurious feeling to automotive interior materials, a covering process (also known as wrapping process), in which an adhesive is applied on an upper portion of a foam layer, and then the foam layer and a core layer are wrapped with natural leather, has been applied to manufacture of automotive interior materials. However, natural leather is expensive and an animal protection issue has recently emerged. Accordingly, there is growing demand for artificial leathers.

For example, KR 10-2018-0078057 A (publication date: Jul. 9, 2018) disclosed a method of manufacturing an automotive interior material using an outermost layer, which is an artificial leather. In this disclosure, a non-woven fabric is used as the back layer of the artificial leather.

However, non-woven fabrics are expensive, and thus are used exclusively in luxury vehicles. In addition, due to the low elongation of non-woven fabrics, when a non-woven fabric is applied, seams are not neat, and workability deteriorates during a covering process. In addition, after the covering process, as shown in FIG. 4, an artificial leather is wrinkled. Another problem is that the conventional artificial leather has too high tensile strength, making it difficult to deploy an airbag easily.

There is increasing demand for development of an artificial leather for automotive interior materials that is inexpensive, may prevent occurrence of wrinkles, allows easy deployment of an airbag, and has excellent durability.

RELATED ART DOCUMENTS

[Patent Documents] (Patent Document 1) KR 10-2018-0078057 A (publication date: Jul. 9, 2018)

DISCLOSURE Technical Problem

Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide an artificial leather for automotive interior materials that is capable of preventing occurrence of wrinkles, allows easy deployment of an airbag, and has excellent durability and a method of manufacturing the artificial leather.

Technical Solution

In accordance with one aspect of the present invention, provided is an artificial leather for automotive interior materials, including:

a back layer, a pore layer, an adhesive layer, and a skin layer laminated in order from bottom to top,

wherein a thickness ratio of the back layer to the pore layer is 1.5 to 3:1,

the pore layer is composed of a non-porous portion positioned at a lower portion thereof and a porous portion positioned at an upper portion thereof, and

an area of 70% or more of the pore layer has a thickness ratio of the non-porous portion to the porous portion of 0.5 to 1.5:1 when a vertical line is drawn from an arbitrary point of an upper end of the pore layer through the lowest point of a pore located at the lowermost position among pores present in the porous portion.

In addition, the artificial leather for automotive interior materials of the present invention may be an artificial leather on which a seam line is formed, and may be used in a covering process of automotive interior materials.

In accordance with another aspect of the present invention, provided is a method of manufacturing an artificial leather for automotive interior materials, the method including back layer formation step S1 of forming a back layer by impregnating a knitted fabric;

skin layer formation step S1′ of forming a skin layer on an upper portion of a release paper;

pore layer formation step S3 of forming a pore layer on an upper portion of the back layer;

adhesive layer formation step S4 of forming an adhesive layer on an upper portion of the skin layer;

skin layer bonding step S5 of bonding the skin layer on which the adhesive layer has been formed to an upper portion of the pore layer; and

release paper removal step S7 of removing the release paper, wherein a thickness ratio of the back layer to the pore layer is 1.5 to 3:1,

the pore layer is composed of a non-porous portion positioned at a lower portion thereof and a porous portion positioned at an upper portion thereof, and

an area of 70% or more of the pore layer has a thickness ratio of the non-porous portion to the porous portion of 0.5 to 1.5:1 when a vertical line is drawn from an arbitrary point of an upper end of the pore layer through the lowest point of a pore located at the lowermost position among pores present in the porous portion.

Advantageous Effects

As apparent from the foregoing, the present invention advantageously provides an artificial leather for automotive interior materials that is capable of preventing occurrence of wrinkles, allows easy deployment of an airbag, and has excellent durability.

In addition, the artificial leather for automotive interior materials of the present invention is inexpensive, has excellent aesthetics and softness, and can prevent transfer of the unevenness of an automotive interior material.

DESCRIPTION OF DRAWINGS

FIG. 1 is a side cross-sectional view schematically showing the laminated structure of an artificial leather for automotive interior materials according to one embodiment of the present invention.

FIG. 2 is a flowchart for explaining a method of manufacturing an artificial leather for automotive interior materials according to one embodiment of the present invention.

FIG. 3 is a top view of a specimen for measuring the elongation and tensile strength of an artificial leather.

FIG. 4 is an image showing the appearance of an automotive interior material covered with an artificial leather for automotive interior materials according to Comparative Example 1.

FIG. 5 is an image showing the appearance of an automotive interior material covered with an artificial leather for automotive interior materials according to the present invention.

FIG. 6 is a scanning electron microscope (SEM) image of a vertical cut surface of an artificial leather, showing a non-porous portion and a porous portion included in the pore layer of the artificial leather.

BEST MODE

The present inventors conducted studies to develop an artificial leather for automotive interior materials that has a seam line and is used in a covering process of automotive interior materials. As a result of such studies, the present inventors confirmed that, when a back layer, a pore layer, an adhesive layer, and a skin layer were laminated in order from bottom to top, and the thickness ratio between a non-porous portion and a porous portion included in the pore layer was adjusted within a specific range, an artificial leather for automotive interior materials that has excellent workability during a covering process, may prevent occurrence of wrinkles after the covering process, allows easy deployment of an airbag, and has excellent durability was implemented. Based on these results, the present inventors conducted further studies to complete the present invention.

Hereinafter, the artificial leather for automotive interior materials of the present invention will be described in detail with reference to the accompanying drawings.

Here, when reference numerals are applied to constituents illustrated in each drawing, it should be noted that like reference numerals indicate like elements throughout the specification.

Referring to FIG. 1, an artificial leather 1 for automotive interior materials of the present invention includes a back layer 10, a pore layer 20, an adhesive layer 30, and a skin layer 40 laminated in order from bottom to top.

The artificial leather 1 for automotive interior materials of the present invention as described above may be an artificial leather used in a covering process of automotive interior materials.

In the present invention, for example, in manufacturing an automotive interior material consisting of an outermost layer and a core layer, the covering process may be a process of applying an adhesive onto the core layer and covering the core layer with an artificial leather as the outermost layer.

As another example, in manufacturing an automotive interior material consisting of an outermost layer, a cushion layer, and a core layer laminated in order from top to bottom, the covering process may be a process of applying an adhesive onto the core layer, covering the core layer with the cushion layer, applying an adhesive onto the cushion layer, and then covering the cushion layer and the core layer with an artificial leather as the outermost layer.

For example, the cushion layer may include one or more selected from the group consisting of polypropylene foam, polyurethane foam, and ethylene-vinyl acetate foam.

Alternatively, as another example, the cushion layer may be a cushion manufactured using one or more synthetic fibers selected from the group consisting of nylon-based fibers, polyester-based fibers, polyolefin-based fibers, polyethylene terephthalate-based fibers, and polypropylene-based fibers.

The core layer may be a hard synthetic resin injection product, and for example, may include one or more synthetic resin injection products selected from the group consisting of polyamides, polycarbonates, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, polyvinylchloride, polystyrene, polyphenylene sulfide, polypropylene, and polyethylene, without being limited thereto.

In addition, in the present invention, the seam line means a tear line for allowing an artificial leather to be ruptured into a certain shape (e.g., H shape, I shape, V shape, etc.) by expansion of an air bag.

The seam line may be formed by a process known in the art for forming a seam line. For example, a seam line having a concave groove shape may be formed on the back surface of an artificial leather using a laser or a knife.

Hereinafter, the laminated structure of the artificial leather 1 for automotive interior materials of the present invention will be described in detail.

Back Layer (10)

According to manufacturing methods, fabrics are broadly classified into non-woven fabrics, woven fabrics, and knitted fabrics.

The non-woven fabric refers to a fabric in which fibers are bonded to each other by chemical treatment, mechanical treatment, or treatment using appropriate moisture and heat.

The woven fabric refers to a fabric formed through a woven fabric process using threads after forming fibers using threads.

The woven fabric, commonly known as fabric, refers to a fabric in which two strands of threads are entangled in the horizontal and vertical directions. That is, the woven fabric refers to a fabric formed by intertwining a thread in the vertical direction (warp) and a thread in the horizontal direction (weft). Depending on the manufacturing methods, the woven fabric may be classified into plain weave, twill weave, and satin weave.

The knitted fabric refers to a fabric formed by connecting loops woven with one thread or two or more threads. According to manufacturing methods, the knitted fabric may be classified into a circular knitted fabric and a warp knitted fabric. The knitted fabric has high elasticity compared to the woven fabric. The circular knitted fabric means a fabric woven by threads supplied in the weft direction, and the warp knitted fabric means a fabric woven by threads supplied in the warp direction.

According to the present invention, when an impregnated knitted fabric is used as the back layer 10, an artificial leather having excellent elongation and tensile strength may be provided at a low cost.

In the present invention, as a specific example, a circular knitted fabric having excellent elongation compared to a wrap knitted fabric may be used as a fabric for forming the back layer 10.

The knitted fabric may be formed using threads having a thickness of 120 to 170 denier or 130 to 160 denier. Within this range, strength may be excellent.

The thread refers to a thread made by twisting one or more fibers selected from natural fibers, regenerated fibers, and synthetic fibers.

The natural fibers may be cotton fibers, hemp fibers, wool fibers, or silk fibers. The regenerated fibers may be rayon fibers or cupra fibers. The synthetic fibers may be polyester fibers, nylon fibers, polyolefin fibers, polyvinyl alcohol fibers, polyamide fibers, polyurethane fibers, or polyvinylidene chloride fibers.

In the present invention, as a specific example, a polyester fiber having excellent elongation may be used as a thread for forming the back layer 10.

In addition, the knitted fabric may be inexpensive, may have shape-retaining properties capable of withstanding repeated stretching and contraction, and may be subjected to impregnation to acquire elongation suitable for a covering process.

In the present invention, impregnation may be performed by performing impregnation in an impregnation solution including a conventionally known solvent-based or aqueous polymer compound, e.g., a polyurethane resin or a copolymer thereof, performing coagulation in an aqueous dimethylformamide solution, and performing rinsing with water.

As a specific example, the impregnation solution may be a polyurethane solution including 200 to 400 parts by weight or 220 to 290 parts by weight of a solvent based on 100 parts by weight of a polyurethane resin.

The solvent may include one or more selected from the group consisting of dimethylformamide, methylethylketone, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and ethyl acetate.

In addition, the impregnation solution may further include other additives such as flame retardants, dispersants, or pigments, and the types and contents thereof are not limited.

For example, the aqueous dimethylformamide solution may include 2 to 10% by weight or 3 to 8% by weight of dimethylformamide and 90 to 98% by weight or 92 to 97% by weight of water.

When a knitted fabric impregnated with the polyurethane solution is used as the back layer 10 of the present invention, an artificial leather capable of withstanding repeated stretching and contraction, having aesthetics such as a soft feel and a sense of volume, having elongation suitable for a covering process, allowing easy deployment of an airbag, and having excellent durability and tensile strength may be provided.

In addition, a single-sided or double-sided brushed knitted fabric may be used as the back layer 10 of the present invention. In this case, adhesion and aesthetics may be excellent.

More specifically, the back layer 10 may be formed by impregnating a knitted fabric in which one or more selected from a surface in contact with the pore layer 20 to be described later and a back surface in contact with a cushion layer by a covering process are brushed.

In addition, the back layer 10 may have a thickness of 0.5 to 1.0 mm, 0.55 to 0.9 mm, or 0.6 to 0.7 mm. Within this range, deterioration of mechanical properties such as tensile strength may be prevented, cost rise may be prevented, and moldability may be maintained.

Specifically, when the thickness of the back layer 10 is less than the above range, the thickness of the back layer 10 in an area where a seam line is formed becomes too thin (for reference, an area where a seam line is formed is about 0.1 to 0.2 mm thinner than an area where a seam line is not formed), thus reducing the durability of an artificial leather. When the thickness of the back layer 10 exceeds the range, cost increases and moldability decreases. Thus, the back layer 10 may have a thickness within the range.

When the thickness of the back layer 10 is measured, the artificial leather for automotive interior materials is cut vertically, and the thickness of the cut section is measured using a scanning electron microscope.

Specifically, when measuring the thickness of the back layer 10, the artificial leather for automotive interior materials is cut vertically, an arbitrary one point on the top surface of the back layer 10 of the vertical cut surface and a point separated by at least 0.5 cm along the top surface from the one point are determined. Then, vertical lines are drawn from the points, and distances from the points to the bottom of the back layer 10 meeting the vertical lines are measured. An average value of the measured distances is taken as the thickness of the back layer 10.

Pore Layer (20)

The pore layer 20 of the present invention has uniform pores formed therein, thereby preventing transfer of the unevenness of an automotive interior material and imparting aesthetics such as a soft feel and a sense of volume, elongation suitable for a covering process, and tensile strength for deployment of an airbag to an artificial leather. As a specific example, the pore layer 20 may be formed using a pore layer composition including 20 to 50 parts by weight of a solvent and 0.5 to 2 parts by weight of a pore control agent based on 100 parts by weight of a polyurethane resin.

More specifically, the pore layer 20 may be formed by coating the top of the back layer with the pore layer composition, performing coagulation in an aqueous dimethylformamide solution, and performing rinsing with water.

For example, the aqueous dimethylformamide solution may include 2 to 10% by weight or 3 to 8% by weight of dimethylformamide and 90 to 98% by weight or 92 to 97% by weight of water. In addition, for example, the coagulation process may be performed for 4 to 8 minutes, preferably 5 to 7 minutes.

Hereinafter, each component of the pore layer composition will be described in detail.

Polyurethane Resin (A)

The polyurethane resin may be prepared by reacting a polyol with diisocyanate and a chain extender.

Specifically, for example, the polyol may include one or more selected from the group consisting of polyether polyols, polyester polyols, and polycarbonate polyols.

The polyether polyol may be derived by reacting a diol or polyol having 2 to 15 carbon atoms, as a specific example, an alkyl diol or glycol and an alkylene oxide having 2 to 6 carbon atoms, as a specific example, ethylene oxide or propylene oxide.

The polyester polyol may be formed by esterifying one or more glycols with one or more dicarboxylic acids or anhydrides thereof. As a specific example, the glycol may include one or more selected from ethylene glycol, propylene glycol, and glycerin, and the dicarboxylic acid may include one or more selected from adipic acid, phthalic acid, and maleic acid.

Alternatively, the polyester polyol may be formed by performing ring-opening polymerization of lactone or a derivative thereof using a small amount of a diol, a triol, or an amine as an initiator. As a specific example, the polyester polyol may be polycaprolactone (PCL) synthesized by performing ring-opening polymerization of ε-caprolactone (CL) using diethylene glycol as an initiator.

The polycarbonate polyol may be derived by reacting a glycol and a carbonate.

In the present invention, as a specific example, the polyol may be prepared by mixing 100 to 150 parts by weight of a polyether polyol and 110 to 200 parts by weight of a polycarbonate polyol based on 100 parts by weight of the polyester polyol. Within this range, mechanical properties, hydrolysis resistance, and chemical resistance may be excellent.

In addition, diisocyanates commonly used in the art may be used as the diisocyanate of the present invention without particular limitation, and the diisocyanate may include one or more selected from the group consisting of aromatic diisocyanates having a benzene ring such as 4,4′-diphenylmethanediisocyanate (MDI), xylene diisocyanate (XDI), and 1,5-naphthalene diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) and propylenediisocyanate; and alicyclic diisocyanates such as 1,4-cyclohexanediisocyanate, isophoronediisocyanate (IPDI), and 4,4′-dicyclohexylmethanediisocyanate (H12MDI).

More specifically, the diisocyanate may include one or more selected from 4,4-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and dicyclohexyl methane diisocyanate (H12MDI).

In addition, chain extenders commonly used in the art may be used as the chain extender of the present invention without particular limitation. As a preferred example, a low molecular weight diol compound or diamine compound having an even number of repeat units, which is advantageous for increasing crystallinity, may be used as the chain extender.

Specifically, the chain extender may include one or more selected from the group consisting of ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), 1,4-butanediol (1,4-BD), 1,6-hexanediol (1,6-HD), methylpentanediol, and isophoronediamine (IPDA).

In addition, for example, the chain extender may be used in an amount of 1 to 15 parts by weight or 2 to 10 parts by weight based on 100 parts by weight of the polyol.

Solvent (B)

The solvent B may include one or more selected from the group consisting of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and ethyl acetate.

In addition, the solvent B may be used in an amount of 20 to 50 parts by weight or 30 to 45 parts by weight based on 100 parts by weight of the polyurethane resin A. When the solvent B is used in an amount less than the range, the viscosity of a pore layer composition is too high, making it difficult to form uniform pores. When the solvent B is used in an amount exceeding the range, the viscosity of a pore layer composition is too low, thereby deteriorating coating properties. Thus, the solvent B may be used within the range.

Pore Control Agent (C)

The pore control agent C is used to form uniform pores in the pore layer 20, and may include one or more surfactants selected from the group consisting of anionic surfactants and nonionic surfactants.

Since the surfactant is composed of a hydrophilic head and a hydrophobic tail, the surfactant may form various micelle structures or liquid crystal structures through self-assembly in an aqueous solution.

For example, the anionic surfactants may include one or more selected from the group consisting of fatty acids (salts) such as oleic acid, palmitic acid, sodium oleate, potassium palmitate, and triethanolamine oleate; carbonates (salts) containing hydroxyl groups such as hydroxyacetic acid, potassium hydroxyacetate, lactic acid, and potassium lactate; polyoxyalkylene alkyl ether acetic acids (salts) such as polyoxyethylene tridecyl ether acetic acid (sodium salt); salts of carboxyl group polysubstituted aromatic compounds such as potassium trimellitate and potassium pyromellitate; alkylbenzenesulfonic acids (salts) such as dodecylbenzenesulfonic acid (sodium salt); polyoxyalkylene alkyl ether sulfonic acids (salts) such as polyoxyethylene 2-ethylhexyl ether sulfonic acid (potassium salt); higher fatty acid amide sulfonic acids (salts) such as stearoylmethyltaurine (sodium), lauroylmethyltaurine (sodium), myristoylmethyltaurine N (sodium), and palmitoylmethyltaurine (sodium); N-acylsarcosinic acids (salts) such as lauroylsarcosinic acid (sodium); alkylphosphonic acids (salts) such as octylphosphonate (potassium salt); aromatic phosphonic acids (salts) such as phenylphosphonate (potassium salt); alkylphosphonic acid alkyl phosphate esters (salts) such as 2-ethylhexylphosphonate mono-2-ethylhexyl ester (potassium salt); nitrogen-containing alkylphosphonic acids (salts) such as aminoethylphosphonic acid (diethanolamine salt); alkyl sulfuric acid esters (salts) such as 2-ethylhexyl sulfate (sodium salt); polyoxyalkylenesulfuric esters (salts) such as polyoxyethylene 2-ethylhexyl ether sulfate (sodium salt); alkyl phosphate esters (salts) such as lauryl phosphate (potassium salt), cetyl phosphate (potassium salt), and stearyl phosphate (diethanolamine salt); polyoxyalkylene alkyl (alkenyl) ether phosphates (salts) such as polyoxyethylene lauryl ether phosphate (potassium salt) and polyoxyethylene oleyl ether phosphate (triethanolamine salt); polyoxyalkylene alkylphenyl ether phosphates (salts) such as polyoxyethylene nonylphenyl ether phosphate (potassium salt) and polyoxyethylene dodecylphenyl ether phosphate (potassium salt); long-chain sulfosuccinate salts such as sodium di-2-ethylhexyl sulfosuccinate and sodium dioctyl sulfosuccinate; and long-chain N-acyl glutamates such as sodium monosodium N-lauroyl glutamate and disodium N-stearoyl-L-glutamate.

For example, the nonionic surfactants may include one or more selected from the group consisting of polyoxyalkylene linear alkyl ethers such as polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, and polyoxyethylene cetyl ether; polyoxyalkylene branched primary alkyl ethers such as polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, and polyoxyethylene isostearyl ether; polyoxyalkylene branched secondary alkyl ethers such as polyoxyethylene 1-hexylhexyl ether, polyoxyethylene 1-octylhexyl ether, polyoxyethylene 1-hexyloctyl ether, polyoxyethylene 1-pentylheptyl ether, and polyoxyethylene 1-heptylpentyl ether; polyoxyalkylene alkenyl ethers such as polyoxyethylene oleyl ether; polyoxyalkylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene dodecylphenyl ether; polyoxyalkylene alkylarylphenyl ethers such as polyoxyethylene tristyrylphenyl ether, polyoxyethylene distyrylphenyl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene tribenzylphenyl ether, polyoxyethylene dibenzylphenyl ether, and polyoxyethylene benzylphenyl ether; polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene monomyristylate, polyoxyethylene dilaurate, polyoxyethylene diolate, polyoxyethylene dimyristylate, and polyoxyethylene distearate; sorbitan esters such as sorbitan monopalmitate and sorbitan monooleate; polyoxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate; glycerin fatty acid esters such as glycerin monostearate, glycerin monolaurate, and glycerin monopalmitate; polyoxyalkylene sorbitol fatty acid esters; sucrose fatty acid esters; polyoxyalkylene castor oil ethers such as polyoxyethylene castor oil ether; polyoxyalkylene hydrogenated castor oil ethers such as polyoxyethylene hydrogenated castor oil ether; polyoxyalkylene alkylamino ethers such as polyoxyethylene lauryl amino ether and polyoxyethylene stearyl amino ether; oxyethylene-oxypropylene blocks or random copolymers; terminal alkyl esterification products of oxyethylene-oxypropylene blocks or random copolymers; and terminal sucrose esterification products of oxyethylene-oxypropylene blocks or random copolymers.

In the present invention, as a specific example, a nonionic surfactant having excellent stability over time may be used as the pore control agent C. More specifically, a polysiloxane modified with polyether may be used as the pore control agent C.

In addition, the pore control agent C may be used in an amount of 0.5 to 2 parts by weight or 0.5 to 1.5 parts by weight based on 100 parts by weight of the polyurethane resin A. When the pore control agent C is used in an amount less than the range, a sufficient number of pores is not formed in the pore layer 20, thereby decreasing a sense of volume. In addition, after completing a process of covering automotive interior materials, some wrinkles may occur in an artificial leather, and prevention of transfer of the unevenness of an automotive interior material may be insignificant. When the pore control agent C is used in an amount exceeding the range, pores may be uneven, and elongation may be reduced, thereby generating some wrinkles in an artificial leather and deteriorating surface properties such as abrasion resistance and stain resistance. Thus, the pore control agent C may be used in an amount within the range.

Optionally, the pore layer composition may further include other additives such as flame retardants, dispersants, and pigments, and the type and content thereof are not limited.

The pore layer 20 of the present invention may consist of a non-porous portion 21 located at the bottom and a porous portion 22 located at the top (see FIG. 1).

The porous portion 22 may be a portion where open pores and/or closed pores are concentrated, and the non-porous portion 21 may be a portion not containing pores (see FIG. 6).

In the present invention, the pores refer to pores having a size of at least 50 μm or more, excluding pores having a size of less than 50 μm.

5 to 20, 7 to 15, or 9 to 13 pores may be included within a cross-sectional area of 0.15 mm² of the porous portion 22. Within this range, transfer of the unevenness of an automotive interior material may be prevented, and an artificial leather having excellent aesthetics such as a soft feel and a sense of volume may be manufactured.

In addition, 60% or more, 70% or more, or 80% or more of pores included in a cross-sectional area of 0.15 mm² of the porous portion 22 may be open pores. Within this range, transfer of the unevenness of an automotive interior material may be prevented, and an artificial leather having excellent aesthetics such as a soft feel and a sense of volume may be manufactured.

In addition, the size of the pores may be 50 to 240 μm, 60 to 180 μm, or 70 to 150 μm. Within this range, transfer of the unevenness of an automotive interior material may be prevented, and an artificial leather having excellent aesthetics, such as a soft feel and a sense of volume, and softness may be manufactured.

In the present invention, pore size means an average value of the diameters of one pore. When pores have a spherical shape, pore size means an average value of diameters. When pores have a shape other than a spherical shape, pore size means an average value of the lengths of major axes.

When the number of pores, the ratio of open pores, and the size of pores are measured, an artificial leather for automotive interior materials is vertically cut, and measurement is performed for a cross-sectional area (width: 0.5 mm, length: 0.3 mm) of 0.15 mm² of the porous portion 22 using a scanning electron microscope.

In addition, in the present invention, an area of 70% or more, 80% or more, 85% or more, or 90% or more may have a thickness ratio of the non-porous portion 21 to the porous portion 22 of 0.5 to 1.5:1, 0.6 to 1.4:1, 0.7 to 1.3:1, or 0.8 to 1.2:1.

When the thickness ratio of the non-porous portion 21 is less than the range, the elongation of an artificial leather may deteriorate, causing wrinkles. In addition, due to high tensile strength, deployment of an airbag may not be easy. When the thickness ratio of the non-porous portion 21 exceeds the range, the aesthetics of an artificial leather, such as a soft feel and a sense of volume, may deteriorate, and due to low elongation, wrinkles may form and appearance may be poor. Thus, the thickness ratio of the non-porous portion 21 may be within the range.

In the present invention, when the thickness ratio of the non-porous portion 21 to the porous portion 22 is measured, an artificial leather for automotive interior materials is vertically cut, a vertical line is drawn from an arbitrary point of an upper end of the pore layer 20 in the cut section through the lowest point of a pore located at the lowermost position among pores of the porous portion 22 using a scanning electron microscope, the thicknesses of the non-porous portion 21 and the porous portion 22 are measured, and the thickness ratio of the non-porous portion 21 to the porous portion 22 is calculated.

Specifically, when measuring the thickness of the porous portion 22, the artificial leather for automotive interior materials is cut vertically, an arbitrary one point on the top surface of the pore layer 20 of the vertical cut surface and a point separated by at least 0.5 cm along the top surface from the one point are determined. Then, vertical lines are drawn from the points through the lowest point of a pore located at the lowermost position among the pores of the porous portion 22, and distances from the top of the pore layer 20 to the lowest point of the pore are measured. An average value of the measured distances is taken as the thickness of the porous portion 22.

In addition, when measuring the thickness of the non-porous portion 21, the artificial leather for automotive interior materials is cut vertically, an arbitrary one point on the top surface of the pore layer 20 of the vertical cut surface and a point separated by at least 0.5 cm along the top surface from the one point are determined. Then, vertical lines are drawn from the points, and distances from the lowest point of a pore located at the lowermost position among pores meeting the vertical lines to the bottom of the pore layer 20 are measured. An average value of the measured distances is taken as the thickness of the non-porous portion 21.

In addition, the thickness of the pore layer 20 may be calculated by averaging the sums of the thicknesses of the non-porous portion 21 and the porous portion 22.

In the present invention, the pore layer 20 may have a thickness of 0.2 to 0.5 mm, 0.2 to 0.4 mm, or 0.25 to 0.35 mm. Within this range, transfer of the unevenness of an automotive interior material may be prevented, elongation and tensile strength suitable for a process of covering an artificial leather may be achieved, and aesthetics such as a soft feel and a sense of volume and softness may be imparted to an artificial leather.

In addition, the thickness of each of the non-porous portion 21 and the porous portion 22 may be 0.08 to 0.42 mm or 0.1 to 0.24 mm. Within this range, elongation and tensile strength suitable for a covering process of automotive interior materials may be achieved, transfer of unevenness may be prevented, and aesthetics such as a soft feel and a sense of volume and softness may be imparted to an artificial leather.

Adhesive Layer (30)

The adhesive layer 30 of the present invention is used to increase adhesion between the pore layer 20 and the skin layer 40, and may be formed using one or more adhesives selected from the group consisting of polyurethane-based adhesives, polyamide-based adhesives, ethylene vinyl acetate-based adhesives, ethylene ethyl acetate-based adhesives, styrene-based thermoplastic elastomers, polyester-based adhesives, ethylene-acrylic copolymers, and polyolefin-based adhesives.

In the present invention, as a specific example, a polyurethane-based adhesive may be used as the adhesive. In this case, the polyurethane-based adhesive may include, for example, 1 to 25 parts by weight or 5 to 20 parts by weight of dimethylformamide, 15 to 45 parts by weight or 20 to 40 parts by weight of methylethylketone, and 5 to 20 parts by weight or 10 to 15 parts by weight of a crosslinking agent based on 100 parts by weight of a polyurethane resin.

The thickness of the adhesive layer 30 may be 0.01 to 0.2 mm or 0.02 to 0.1 mm. Within this range, adhesion between the pore layer 20 and the skin layer 40 may be increased.

Skin Layer (40)

The skin layer 40 of the present invention is formed to implement a texture similar to that of a natural leather. As a specific example, the skin layer 40 may be formed using a skin layer composition including 10 to 60 parts by weight of a solvent and 10 to 40 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin.

More specifically, the skin layer 40 may be formed by applying the skin layer composition to an upper portion of a release paper and drying the release paper.

The polyurethane resin may include one or more polyurethane resins selected from the group consisting of polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, polyacetal polyurethane, polyacrylate polyurethane, polyester amide polyurethane, polythioether polyurethane, and polyolefin polyurethane.

In the present invention, as a specific example, a polycarbonate polyurethane resin having excellent hydrolysis resistance and heat resistance may be used as the polyurethane resin.

The solvent may include one or more selected from the group consisting of dimethylformamide, methylethylketone, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and ethyl acetate.

In addition, the solvent may be used in an amount of 10 to 60 parts by weight or 20 to 55 parts by weight based on 100 parts by weight of a polyurethane resin. Within this range, coating properties may be excellent.

Pigments commonly used in the art may be used as the pigment of the present invention, and the content thereof is not limited. For example, the pigment may be used in an amount of 10 to 40 parts by weight or 10 to 25 parts by weight based on 100 parts by weight of a polyurethane resin.

In addition, optionally, the skin layer composition may further include one or more additives selected from the group consisting of UV inhibitors, light stabilizers, antioxidants, flame retardants, slip agents, antistatic agents, dispersants, and surfactants, and the contents and types thereof are not limited within the scope of the present invention.

In addition, the skin layer 40 may have a thickness of 0.01 to 0.3 mm or 0.02 to 0.1 mm. Within this range, a texture similar to that of a natural leather may be implemented, and elongation may be increased.

In addition, optionally, the artificial leather 1 for automotive interior materials of the present invention may further include a surface treatment layer (not shown) for adjusting the surface gloss of the skin layer 40 and improving light resistance, hydrolysis resistance, and chemical resistance.

Specifically, the surface treatment layer may be formed by applying a surface treatment agent onto the surface of the skin layer 40.

The surface treatment agent may be a water-based surface treatment agent or an oil-based surface treatment agent. As a specific example, the surface treatment agent may be a two-component water-based surface treatment agent including 1 to 30 parts by weight or 1 to 25 parts by weight of a curing agent, 1 to 30 parts by weight or 1 to 25 parts by weight of a water-based solvent, and 1 to 10 parts by weight or 1 to 5 parts by weight of a silicon compound based on 100 parts by weight of a main material.

The main material may be a water-dispersed polycarbonate-based polyurethane resin without being limited thereto.

The curing agent may include one or more functional groups selected from the group consisting of an aziridine group, an isocyanate group, and a carbodiimide group per molecule.

The silicon compound may be polysiloxane in the form of liquid in which polysiloxane is dispersed in water or polysiloxane in the form of beads, but is preferably polysiloxane in the form of liquid with a good surface texture.

The water-based solvent may be water, an alcohol, or a mixture thereof.

The silicon compound may be polysiloxane in the form of liquid in which polysiloxane is dispersed in water or polysiloxane in the form of beads, but is preferably polysiloxane in the form of liquid with a good surface texture.

The surface treatment layer may have a thickness of 1 to 20 μm or 5 to 10 μm, without being limited thereto.

The artificial leather for automotive interior materials of the present invention may have a thickness of 0.85 to 1.5 mm, 0.9 to 1.3 mm, or 0.95 to 1.2 mm. Within this range, occurrence of wrinkles may be prevented, and a covering process may be easy.

In addition, in the artificial leather of the present invention, the thickness ratio of the back layer 10 to the pore layer 20 may be 1.5 to 3:1, 1.6 to 2.9:1, 1.7 to 2.8:1, or 1.8 to 2.7:1. When the thickness ratio of the back layer 10 is less than the range, the back layer 10 in an area where the seam line is formed becomes too thin, thus reducing the durability of an artificial leather. When the thickness ratio of the back layer 10 exceeds the range, the pore layer 20 becomes relatively thin, and thus prevention of transfer of the unevenness of an automotive interior material may be insignificant. In addition, the aesthetics of an artificial leather, such as a soft feel and a sense of volume, may deteriorate, and due to too high elongation, wrinkles may occur. Thus, the thickness ratio may be within the range.

In addition, in the artificial leather of the present invention, an area of 70% or more, 80% or more, 85% or more, or 90% or more may have a thickness ratio of the back layer 10 to the pore layer 20 of 1.5 to 3:1, 1.6 to 2.9:1, 1.7 to 2.8:1, or 1.8 to 2.7:1.

When the thickness ratio of the back layer 10 to the pore layer 20 is measured, an artificial leather for automotive interior materials is vertically cut, the thicknesses of each layer at the cut section are measured using a scanning electron microscope, and the thickness ratio of the back layer 10 to the pore layer 20 is calculated.

Specifically, a method of measuring the thicknesses of the back layer 10 and the pore layer 20 is the same as that described above, and thus repeated description thereof will be omitted.

In addition, the artificial leather for automotive interior materials of the present invention may have an elongation of 80 to 180% or 90 to 170% in the length direction and an elongation of 110 to 290% or 120 to 280% in the width direction. Within this range, occurrence of wrinkles in the artificial leather for automotive interior materials may be prevented.

Specifically, when the elongation of the artificial leather for automotive interior materials is less than the range, wrinkles may occur in the artificial leather for automotive interior materials, and thus appearance may be defective. In addition, it is difficult to pull the artificial leather during a process of covering an automotive interior material, i.e., workability may deteriorate. When the elongation of the artificial leather exceeds the range, wrinkles may occur in the artificial leather for automotive interior materials, and an embossed pattern formed on the artificial leather may be stretched to make the emboss pattern uneven, resulting in appearance defects.

In the present invention, the length direction means a machine direction (MD), and the width direction means a transverse direction (TD) perpendicular to the machine direction.

In the present invention, elongation may be measured using a tensile tester (Instron Co.). After drawing a mark M of 100 mm on a specimen, the specimen is fixed to the tester and tensioned at 200 mm/min, and elongation when the specimen is broken is calculated according to Equation 1.

L=(L ₁ −L ₀)/L ₀×100  [Equation 1]

(Here, L: elongation (%), L₀: distance between marked points before test, L₁: distance between marked points when skin or bubbles break after test)

In addition, the artificial leather for automotive interior materials of the present invention may have a tensile strength of 30 to 80 kgf/30 mm or 35 to 70 kgf/30 mm in the length direction and a tensile strength of 20 to 70 kgf/30 mm or 25 to 60 kgf/30 mm in the width direction. Within this range, the artificial leather for automotive interior materials may have excellent durability, and easy deployment of an airbag may be possible.

Specifically, when the tensile strength of the artificial leather for automotive interior materials is less than the range, the durability of the artificial leather for automotive interior materials may be reduced. When the tensile strength of the artificial leather exceeds the range, deployment of an airbag may not be easy. In the present invention, tensile strength may be measured using a tensile tester (Instron Co.). After drawing a mark M of 100 mm on a specimen, the specimen is fixed to the tester and tensioned at 200 mm/min, and maximum weight when the specimen is broken is measured.

In addition, the artificial leather for automotive interior materials of the present invention may have a softness of 3.6 to 4.5 or 3.6 to 4.4. Within this range, aesthetics such as a soft feel and a sense of volume may be excellent.

In the present invention, when softness is measured, under conditions of a temperature of 23±2° C. and a relative humidity of 50±5%, an artificial leather specimen having a pi (n) of 100 mm is pressed with a softness measurement device (SDL Atlas, ST300D), and softness is determined by reading a scale that has been moved for 15 seconds.

In addition, in the artificial leather for automotive interior materials of the present invention, the content of polyurethane in the back layer 10 and the pore layer 20 may be 200 to 700 g/m², 250 to 600 g/m², or 300 to 500 g/m². Within this range, the artificial leather for automotive interior materials may have excellent workability during a covering process, and occurrence of wrinkles may be prevented after the covering process. In addition, easy deployment of an airbag may be possible, and excellent durability may be acquired.

When the content of polyurethane in the back layer 10 and the pore layer 20 is measured, the back layer 10 and the pore layer 20 are impregnated with dimethylformamide so that a polyurethane resin is dissolved in the back layer 10 and the pore layer 20, dimethylformamide is evaporated, and then the weight (g/m²) of the back layer 10 and the pore layer 20 is measured to determine the reduced weight of the back layer 10 and the pore layer 20. Based on these measurement results, the content of the polyurethane resin in the back layer 10 and the pore layer 20 is calculated.

In addition, the artificial leather for automotive interior materials of the present invention may be used in one or more automotive interior materials selected from the group consisting of a crash pad, a door trim, a console box, an armrest, a headrest, and a headliner.

The artificial leather 1 for automotive interior materials of the present invention as described above may prevent occurrence of wrinkles in automotive interior materials, may allow easy deployment of an airbag, and may have excellent durability.

In addition, the artificial leather 1 for automotive interior materials of the present invention may be inexpensive, may have excellent aesthetics and softness, and may prevent transfer of the unevenness of an automotive interior material.

In addition, the present invention relates to a method of manufacturing an artificial leather for automotive interior materials, the method including:

back layer formation step S1 of forming a back layer by impregnating a knitted fabric;

skin layer formation step S1′ of forming a skin layer on an upper portion of a release paper;

pore layer formation step S3 of forming a pore layer on an upper portion of the back layer;

adhesive layer formation step S4 of forming an adhesive layer on an upper portion of the skin layer;

skin layer bonding step S5 of bonding the skin layer on which the adhesive layer has been formed to an upper portion of the pore layer; and

release paper removal step S7 of removing the release paper,

wherein the thickness ratio of the back layer to the pore layer is 1.5 to 3:1,

the pore layer is composed of a non-porous portion positioned at a lower portion thereof and a porous portion positioned at an upper portion thereof, and

an area of 70% or more of the pore layer has a thickness ratio of the non-porous portion to the porous portion of 0.5 to 1.5:1 when a vertical line is drawn from an arbitrary point of an upper end of the pore layer through the lowest point of a pore located at the lowermost position among pores present in the porous portion (see FIG. 2).

Hereinafter, each step will be described in detail.

Back Layer Formation Step (S1)

Back layer formation step S1 may be a step of impregnating a knitted fabric with an impregnation solution.

Specifically, the knitted fabric is impregnated with an impregnation solution (for example, polyurethane solution), coagulated in an aqueous dimethylformamide solution, and rinsed with water. Thereby, the knitted fabric is impregnated with a specific amount of a polyurethane resin. Thus, a finished product, artificial leather, has aesthetics such as a soft feel and a sense of volume, shape-retaining properties capable of withstanding repeated stretching and contraction, and elongation and tensile strength suitable for a covering process and deployment of an airbag.

The knitted fabric, the impregnation solution, and the aqueous dimethylformamide solution have been described in detail above, and thus repeated description thereof will be omitted.

Alternatively, optionally, before impregnating a knitted fabric with an impregnation solution, back layer formation step S1 may further include buffing process step S0 of forming a brush on one or both sides of the knitted fabric. In this case, adhesion and aesthetics may be excellent.

Skin Layer Formation Step (S1′)

Skin layer formation step S1′ may be a step of applying a skin layer composition onto an upper portion of a release paper and drying the release paper to form a skin layer separately from back layer formation step S1.

An embossed pattern may be formed on the release paper.

In addition, detailed description of the skin layer composition is the same as that described above, and thus repeated description thereof will be omitted.

For example, the application may be performed using one method selected from bar coating, knife coating, roll coating, slit coating, screen printing, and spray coating, without being limited thereto.

The drying may be performed at a temperature of 60 to 125° C. or 65 to 120° C. for 1 to 10 minutes or 3 to 7 minutes until the skin layer composition containing polyurethane is completed dried.

Pore Layer Formation Step (S3)

Pore layer formation step S3 may be a step of forming a pore layer on an upper portion of the back layer.

Specifically, the upper portion of the back layer is coated with a pore layer composition, and the back layer is coagulated in an aqueous dimethylformamide solution and rinsed with water to form a wet coating layer with uniform fine pores. Then, the back layer is dried to form a pore layer.

In the present invention, the wet coating layer is a fine pores-containing layer formed by applying the pore layer composition onto an upper portion of a back layer, coagulating the back layer in an aqueous dimethylformamide solution, and rinsing the back layer with water.

Detailed description of the pore layer composition is the same as that described above, and thus repeated description thereof will be omitted.

In addition, pore layer formation step S3 and skin layer formation step S1′ are independent of each other, and thus the order of the previous step and the subsequent step may be changed.

Adhesive Layer Formation Step (S4)

Adhesive layer formation step S4 may be a step of applying an adhesive onto an upper portion of the skin layer to increase adhesion between the skin layer and the pore layer and performing drying to form an adhesive layer. Drying of the adhesive may performed at a temperature of 70 to 120° C. or 75 to 110° C. for 30 seconds to 5 minutes or 1 minute to 3 minutes.

In addition, adhesive layer formation step S4 and pore layer formation step S3 are independent of each other, and thus the order of the two steps may be reversed, provided that the two steps are performed after skin layer formation step S1′.

Detailed description of the adhesive is the same as that described above, and thus repeated description thereof will be omitted.

Skin Layer Bonding Step (S5)

Skin layer bonding step S5 may be a step of bonding the skin layer and the pore layer. In this step, aging may be performed at a temperature of 60 to 95° C. or 70 to 90° C. for 40 to 60 hours or 45 to 55 hours.

Release Paper Removal Step (S7)

Release paper removal step S7 may be a step of peeling release paper located on one surface of the skin layer. After this step, the artificial leather for automotive interior materials of the present invention including the back layer, which is an impregnated knitted fabric; the pore layer; the adhesive layer; and the skin layer laminated in order from bottom to top is manufactured.

Optionally, the method of manufacturing an artificial leather for automotive interior materials of the present invention may further include, after release paper removal step S7, step S9 of applying a surface treatment agent onto an upper portion of the skin layer to form a surface treatment layer.

Specifically, the surface treatment layer may be formed by applying a surface treatment agent onto an upper portion of the skin layer, the uppermost layer, from which the release paper has been removed, and performing drying.

Detailed description of the surface treatment agent is the same as that described above, and thus repeated description thereof will be omitted.

Hereinafter, the present invention will be described in more detail with reference to the following preferred examples. However, these examples are provided for illustrative purposes only and should not be construed as limiting the scope and spirit of the present invention. In addition, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention, and such changes and modifications are also within the scope of the appended claims.

EXAMPLES 1. Manufacturing of Artificial Leather for Automotive Interior Materials Example 1

(1) Back Layer Formation Step (S1)

After impregnating a circular knitted fabric formed by weaving a polyester thread having a thickness of 120 to 170 denier with an impregnation solution, the circular knitted fabric was coagulated in a 5% aqueous dimethylformamide solution and rinsed with water to form a back layer impregnated with a polyurethane resin and having a thickness of 0.65 mm.

In this case, the impregnation solution was a polyurethane solution including 250 parts by weight of dimethylformamide, 25 parts by weight of a flame retardant, and 30 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin.

(2) Pore Layer Formation Step (S3)

The upper portion of the back layer was coated with a pore layer composition including 35 parts by weight of dimethylformamide, 1 part by weight of a pore control agent (BYK-L 9525, Uni-Material Co.), 10 parts by weight of a flame retardant, 0.5 parts by weight of a dispersant (DISPERBYK-130, BYK KOREA Co.), and 10 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin. Then, the back layer was coagulated in a 5% aqueous dimethylformamide solution for 5 minutes and rinsed with water to form a wet coating layer with uniform fine pores. Then, the back layer was dried using a heat tender so that a pore layer having a thickness of 0.3 mm was formed on the upper portion of the back layer.

In this case, in the pore layer, the thickness of a non-porous portion was 0.13 mm, and the thickness of a porous portion was 0.17 mm.

(3) Skin Layer Formation Step (S1′)

A skin layer composition including 15 parts by weight of dimethylformamide, 30 parts by weight of methylethylketone, and 15 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin was applied onto the upper portion of a release paper on which an embossed pattern was formed, and the release paper was dried at 100° C. for 5 minutes to form a skin layer having a thickness of 0.04 mm.

(4) Adhesive Layer Formation Step (S4)

A polyurethane-based adhesive including 5 to 20 parts by weight of dimethylformamide, 20 to 40 parts by weight of methylethylketone, and 10 to 15 parts by weight of a crosslinking agent based on 100 parts by weight of a polyurethane resin was applied onto the upper portion of the skin layer, and curing was performed at 90° C. for 1 minute to form an adhesive layer having a thickness of 0.08 mm.

(5) Skin Layer Bonding Step (S5) and Release Paper Removal Step (S7)

The adhesive layer on the upper portion of the skin layer was bonded to the pore layer, aging was performed at 80° C. for 48 hours, and then the release paper on the bottom of the skin layer was peeled off.

(6) Surface Treatment Layer Formation Step (S9)

A two-component water-based surface treatment agent including 1 to 25 parts by weight of a curing agent, 1 to 25 parts by weight of a water-based solvent, and 1 to 5 parts by weight of a silicon compound based on 100 parts by weight of a polyurethane resin as a main material was applied onto the upper portion of the skin layer from which the release paper had been peeled off to form a surface treatment layer having a thickness of 10 μm.

Using a Thomson press machine (SW-900S, Sewoong Industrial Co.), a seam line was formed on the back layer of the artificial leather for automotive interior materials having a thickness of 1.08 mm manufactured according to Example 1.

Example 2

Procedures were performed in the same manner as in Example 1, except that pore layer formation step S3 was performed as follows.

(2) Pore Layer Formation Step (S3)

The upper portion of the back layer was coated with a pore layer composition including 35 parts by weight of dimethylformamide, 1.3 parts by weight of a pore control agent (BYK-L 9525, Uni-Material Co.), 10 parts by weight of a flame retardant, 0.5 parts by weight of a dispersant (DISPERBYK-130, BYK KOREA Co.), and 10 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin. Then, the back layer was coagulated in a 5% aqueous dimethylformamide solution for 7 minutes and rinsed with water to form a wet coating layer with uniform fine pores. Then, the back layer was dried using a heat tender so that a pore layer having a thickness of 0.3 mm was formed on the upper portion of the back layer.

In this case, in the pore layer, the thickness of a non-porous portion was 0.10 mm, and the thickness of a porous portion was 0.2 mm.

Example 3

Procedures were performed in the same manner as in Example 1, except that pore layer formation step S3 was performed as follows.

(2) Pore Layer Formation Step (S3)

The upper portion of the back layer was coated with a pore layer composition including 35 parts by weight of dimethylformamide, 0.8 parts by weight of a pore control agent (BYK-L 9525, Uni-Material Co.), 10 parts by weight of a flame retardant, 0.5 parts by weight of a dispersant (DISPERBYK-130, BYK KOREA Co.) and 10 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin. Then, the back layer was coagulated in a 5% aqueous dimethylformamide solution for 4 minutes and rinsed with water to form a wet coating layer with uniform fine pores. Then, the back layer was dried using a heat tender so that a pore layer having a thickness of 0.3 mm was formed on the upper portion of the back layer.

In this case, in the pore layer, the thickness of a non-porous portion was 0.15 mm, and the thickness of a porous portion was 0.15 mm.

Comparative Example 1

(1) Back Layer Formation Step (S1)

After forming webs using single fiber sea-island yarn having a weight ratio of nylon (island component) to polyester (sea component) of 60 to 80:40 to 50, a plurality of webs was bonded by needle punching to prepare a non-woven fabric.

Then, the non-woven fabric was subjected to a weight loss process in a 5% aqueous NaOH solution to dissolve the sea component, and then polishing was performed to form a back layer having a thickness of 0.65 mm that was an ultra-fine non-woven fabric.

(2) Pore layer formation step (S3): Not performed.

(3) Skin Layer Formation Step (S1′)

A skin layer composition including 15 parts by weight of dimethylformamide, 30 parts by weight of methylethylketone, and 15 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin was applied onto the upper portion of a release paper on which an embossed pattern was formed, and the release paper was dried at 100° C. for 5 minutes to form a skin layer having a thickness of 0.04 mm.

(4) Adhesive Layer Formation Step (S4)

A polyurethane-based adhesive including 5 to 20 parts by weight of dimethylformamide, 20 to 40 parts by weight of methylethylketone, and 10 to 15 parts by weight of a crosslinking agent based on 100 parts by weight of a polyurethane resin was applied onto the upper portion of the skin layer, and curing was performed at 90° C. for 1 minute to form an adhesive layer having a thickness of 0.38 mm.

(5) Skin Layer Bonding Step (S5) and Release Paper Removal Step (S7)

The adhesive layer on the upper portion of the skin layer was bonded to the pore layer, aging was performed at 80° C. for 48 hours, and then the release paper on the bottom of the skin layer was peeled off.

(6) Surface Treatment Layer Formation Step (S9)

An oil-based surface treatment agent including 95% by weight of urethane acrylate and 5% by weight of methylene dicyclohexyl diisocyanate as a curing agent was applied onto the upper portion of the skin layer from which the release paper had been peeled off. Thereby, a surface treatment layer having a thickness of 10 μm was formed.

Using a Thomson press machine (SW-900S, Sewoong Industrial Co.), a seam line was formed on the back layer of the artificial leather for automotive interior materials having a thickness of 1.08 mm manufactured according to Comparative Example 1.

Comparative Example 2

(1) Back Layer Formation Step (S1)

After impregnating a circular knitted fabric formed by weaving a polyester thread having a thickness of 120 to 170 denier with an impregnation solution, the circular knitted fabric was coagulated in a 5% aqueous dimethylformamide solution and rinsed with water to form a back layer impregnated with a polyurethane resin and having a thickness of 0.65 mm.

In this case, the impregnation solution was a polyurethane solution including 250 parts by weight of dimethylformamide, 25 parts by weight of a flame retardant, and 30 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin.

(2) Pore layer formation step (S3): Not performed.

(3) Skin Layer Formation Step (S1′)

A skin layer composition including 15 parts by weight of dimethylformamide, 30 parts by weight of methylethylketone, and 15 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin was applied onto the upper portion of a release paper on which an embossed pattern was formed, and the release paper was dried at 100° C. for 5 minutes to form a skin layer having a thickness of 0.04 mm.

(4) Adhesive Layer Formation Step (S4)

A polyurethane-based adhesive including 5 to 20 parts by weight of dimethylformamide, 20 to 40 parts by weight of methylethylketone, and 10 to 15 parts by weight of a crosslinking agent based on 100 parts by weight of a polyurethane resin was applied onto the upper portion of the skin layer, and curing was performed at 90° C. for 1 minute to form an adhesive layer having a thickness of 0.38 mm.

(5) Skin Layer Bonding Step (S5) and Release Paper Removal Step (S7)

The adhesive layer on the upper portion of the skin layer was bonded to the pore layer, aging was performed at 80° C. for 48 hours, and then the release paper on the bottom of the skin layer was peeled off.

(6) Surface Treatment Layer Formation Step (S9)

A two-component water-based surface treatment agent including 1 to 25 parts by weight of a curing agent, 1 to 25 parts by weight of a water-based solvent, and 1 to 5 parts by weight of a silicon compound based on 100 parts by weight of a polyurethane resin as a main material was applied onto the upper portion of the skin layer from which the release paper had been peeled off to form a surface treatment layer having a thickness of 10 μm.

Using a Thomson press machine (SW-900S, Sewoong Industrial Co.), a seam line was formed on the back layer of the artificial leather for automotive interior materials having a thickness of 1.08 mm manufactured according to Comparative Example 2.

Comparative Example 3

Procedures were performed in the same manner as in Example 1, except that pore layer formation step S3 was performed as follows.

(2) Pore Layer Formation Step (S3)

The upper portion of the back layer was coated with a pore layer composition including 35 parts by weight of dimethylformamide, 1.5 parts by weight of a pore control agent (BYK-L 9525, Uni-Material Co.), 10 parts by weight of a flame retardant, 0.5 parts by weight of a dispersant (DISPERBYK-130, BYK KOREA Co.), and 10 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin. Then, the back layer was coagulated in a 5% aqueous dimethylformamide solution for 10 minutes and rinsed with water to form a wet coating layer with uniform fine pores. Then, the back layer was dried using a heat tender so that a pore layer having a thickness of 0.3 mm was formed on the upper portion of the back layer.

In this case, in the pore layer, the thickness of a non-porous portion was 0.05 mm, and the thickness of a porous portion was 0.25 mm.

Comparative Example 4

Procedures were performed in the same manner as in Example 1, except that pore layer formation step S3 was performed as follows.

(2) Pore Layer Formation Step (S3)

The upper portion of the back layer was coated with a pore layer composition including 35 parts by weight of dimethylformamide, 0.7 parts by weight of a pore control agent (BYK-L 9525, Uni-Material Co.), 10 parts by weight of a flame retardant, 0.5 parts by weight of a dispersant (DISPERBYK-130, BYK KOREA Co.) and 10 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin. Then, the back layer was coagulated in a 5% aqueous dimethylformamide solution for 3 minutes and rinsed with water to form a wet coating layer with uniform fine pores. Then, the back layer was dried using a heat tender so that a pore layer having a thickness of 0.3 mm was formed on the upper portion of the back layer.

In this case, in the pore layer, the thickness of a non-porous portion was 0.25 mm, and the thickness of a porous portion was 0.05 mm.

2. Evaluation of Physical Properties and Aesthetics of Artificial Leather for Automotive Interior Materials

For the artificial leathers manufactured in Examples 1 to 3 and Comparative Examples 1 to 4, elongation, tensile strength, softness, and the thickness of each layer were measured. It was determined whether transfer of unevenness and occurrence of wrinkles were prevented after a covering process of automotive interior materials, and aesthetics (a soft feel and a sense of volume) were evaluated. The results are shown in Table 1 below.

Specifically, the elongation, tensile strength, softness, and thickness of the artificial leather were measured before a seam line was formed. Whether transfer of unevenness and occurrence of wrinkles were prevented and aesthetics were evaluated after a seam line was formed and a covering process of automotive interior materials was completed.

Specific measurement methods are as follows.

(1) Elongation: Elongation was measured using a tensile tester (Instron Co.). After drawing a mark (l) of 100 mm on the specimen of FIG. 3, the specimen was fixed to the tester and tensioned at 200 mm/min, and elongation when the specimen was broken was calculated according to Equation 1.

L=(L ₁ −L ₀)/L ₀×100  [Equation 1]

(Here, L: elongation (%), L₀: distance between marked points before test, L₁: distance between marked points when skin or bubbles break after test)

(2) Tensile strength: Tensile strength was measured using a tensile tester (Instron Co.). After drawing a mark M of 100 mm on the specimen of FIG. 3, the specimen was fixed to the tester and tensioned at 200 mm/min, and maximum weight when the specimen was broken was measured.

(3) Whether transfer of unevenness is prevented: After completing a covering process of automotive interior materials with the artificial leather, whether transfer of unevenness occurred was visually confirmed.

When transfer of unevenness was observed entirely, it was marked with “X”. When transfer of unevenness was observed partially, it was marked with “Δ”. When transfer of unevenness was not observed, it was marked with “∘”.

(4) Whether occurrence of wrinkles is prevented: After completing a covering process of automotive interior materials with the artificial leather, whether occurrence of wrinkles was prevented was visually confirmed.

When wrinkles were observed entirely, it was marked with “X”. When wrinkles were observed partially, it was marked with “Δ”. When no wrinkles were observed, it was marked with “◯”.

(5) Aesthetics: After completing a covering process of automotive interior materials with the artificial leather, experts directly touched the artificial leather to check a soft feel and a sense of volume.

When aesthetics was excellent, it was marked with “◯”. When aesthetics was ordinary, it was marked with “Δ”. When aesthetics was poor, it was marked with “X”.

(6) Softness: Under conditions of a temperature of 23±2° C. and a relative humidity of 50±5%, an artificial leather specimen having a pi (n) of 100 mm was pressed with a softness measurement device (SDL Atlas, ST300D), and softness was determined by reading a scale that had been moved for 15 seconds.

(7) Thickness of Each Layer of Artificial Leather

The artificial leather was cut vertically, and the cut section was photographed using a scanning electron microscope (magnification: 300×) (SU8010, Hitachi Co.). The thickness of each layer of the artificial leather was measured using the obtained image.

Among the layers of the artificial leather, the surface treatment layer, the skin layer, and the adhesive layer with relatively uniform thickness showed similar values even when measuring various points. Thus, an arbitrary one point on the top surface of each layer and a point separated by at least 0.5 cm along the top surface from the one point were determined. Then, a vertical line was drawn from the points, and a distance from the points to the bottom of each layer meeting the vertical line was taken as the thickness of the layer.

In addition, when measuring the thickness of the back layer, an arbitrary one point on the top surface of the back layer and a point separated by at least 0.5 cm along the top surface from the one point were determined. Then, vertical lines were drawn from the points, and distances from the points to the bottom of the back layer meeting the vertical lines were measured. An average value of the measured distances was taken as the thickness of the back layer. The thickness of the pore layer was calculated by averaging the sums of the thicknesses of the non-porous portion and the porous portion.

In addition, thickness ratio was calculated using the thicknesses of the back layer and the pore layer.

(8) Thicknesses of Non-Porous Portion and Porous Portion in Pore Layer

The artificial leather was cut vertically, and the cut section was photographed using a scanning electron microscope (magnification: 300×) (SU8010, Hitachi Co.). Using the obtained image, the thicknesses of the porous portion and the non-porous portion were measured.

Specifically, when measuring the thickness of the porous portion, the artificial leather for automotive interior materials was cut vertically, an arbitrary one point on the top surface of the pore layer of the vertical cut surface and a point separated by at least 0.5 cm along the top surface from the one point were determined. Then, vertical lines were drawn from the points through the lowest point of a pore located at the lowermost position among the pores of the porous portion, and distances from the top of the pore layer to the lowest point of the pore were measured. An average value of the measured distances was taken as the thickness of the porous portion.

In addition, when measuring the thickness of the non-porous portion, the artificial leather for automotive interior materials was cut vertically, an arbitrary one point on the top surface of the pore layer of the vertical cut surface and a point separated by at least 0.5 cm along the top surface from the one point were determined. Then, vertical lines were drawn from the points through the lowest point of a pore located at the lowermost position among the pores of the porous portion, and distances from the lowest point of the pore to the bottom of the pore layer were measured. An average value of the measured distances was taken as the thickness of the non-porous portion.

In addition, thickness ratio was calculated based on the thicknesses of the non-porous portion and the porous portion.

TABLE 1 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Example 4 Surface Thickness 0.01 0.01 0.01 0.01 0.01 0.01 0.01 treatment (mm) layer Skin layer Thickness 0.04 0.04 0.04 0.04 0.04 0.04 0.04 (mm) Adhesive Thickness 0.08 0.08 0.08 0.38 0.38 0.08 0.08 layer (mm) Pore layer Presence/ ◯ ◯ ◯ X X ◯ ◯ absence Thickness 0.13 0.10 0.15 — — 0.05 0.25 of non- porous portion (mm) Thickness 0.17 0.20 0.15 — — 0.25 0.05 of porous portion (mm) Thickness 0.76:1 0.5:1 1:1 — — 0.2:1 5:1 ratio of non- porous portion to porous portion Back layer Types Impregnated Impregnated Impregnated Impregnated Non- Impregnated Impregnated circular circular circular circular impregnated circular circular knitted knitted knitted knitted non-woven knitted knitted fabric fabric fabric fabric fabric fabric fabric Thickness 0.65 0.65 0.65 0.65 0.65 0.65 0.65 (mm) Thickness ratio of back 2.2:1 2.2:1 2.2:1 — — 2.2:1 2.2:1 layer to pore layer Artificial Thickness 1.08 1.08 1.08 1.08 1.08 1.08 1.08 leather (mm) Physical properties Elongation Length 128 110 92 40 68 73 75 (%) (MD) Width 182 160 197 60 295 239 103 (TD) Tensile Length 50 45 50 87 80 84 84 strength (MD) (kgf/30 mm) Width 45 44 40 72 52 25.2 41 (TD) Prevention of transfer ◯ ◯ ◯ X X ◯ Δ of unevenness Prevention of occurrence ◯ ◯ ◯ X X Δ Δ of wrinkles Aesthetics ◯ ◯ ◯ X Δ ◯ Δ Softness 4.2 4.0 4.0 2.3 3 4.6 3.2

As shown in Table 1, the artificial leathers for automotive interior materials including a seam line of Examples 1 to 3 include a back layer, a pore layer, an adhesive layer, and a skin layer laminated in order from bottom to top. In this case, the thickness ratio of the non-porous portion to the porous portion in the pore layer is 0.5 to 1.5:1. Thus, due to excellent elongation, occurrence of wrinkles is prevented, and due to excellent tensile strength, deployment of an airbag may be easy and durability may be increased. In addition, transfer of the unevenness of an automotive interior material is prevented, and aesthetics and softness are excellent (see FIG. 5).

On the other hand, in the case of the artificial leather of Comparative Example 1 using a non-impregnated non-woven fabric as the back layer, due to low elongation, occurrence of wrinkles is not prevented. In addition, compared to the artificial leathers of Examples 1 to 3, due to high tensile strength, deployment of an airbag may not be easy, and aesthetics and softness deteriorate. In particular, due to the absence of a pore layer, prevention of transfer of unevenness is insignificant.

In addition, since the artificial leather of Comparative Example 2 using an impregnated circular knitted fabric as the back layer does not include a pore layer, elongation is reduced, causing occurrence of wrinkles, and transfer of unevenness is not prevented. In addition, compared to the artificial leathers of Examples 1 to 3, aesthetics and softness deteriorate.

In addition, in the case of the artificial leather of Comparative Example 3 using an impregnated circular knitted fabric as the back layer but not satisfying the thickness ratio of the non-porous portion to the porous portion of 0.5 to 1.5:1 (i.e., the porous portion is much thicker than the non-porous portion), due to low elongation, an anti-wrinkle effect is insignificant compared to the artificial leathers of Examples 1 to 3, and due to high tensile strength, deployment of an airbag may be not easy.

In addition, in the case of the artificial leather of Comparative Example 4 using an impregnated circular knitted fabric as the back layer but not satisfying the thickness ratio of the non-porous portion to the porous portion of 0.5 to 1.5:1 (i.e., the porous portion is much thinner than the non-porous portion), due to low elongation, an anti-wrinkle effect is insignificant compared to the artificial leathers of Examples 1 to 3, and due to high tensile strength, deployment of an airbag may be not easy. In addition, prevention of transfer of unevenness is insignificant, and aesthetics and softness deteriorate.

DESCRIPTION OF SYMBOLS

 1: ARTIFICIAL LEATHER FOR AUTOMOTIVE INTERIOR MATERIALS 10: BACK LAYER 20: PORE LAYER 21: NON-POROUS PORTION 22: POROUS PORTION 30: ADHESIVE LAYER 40: SKIN LAYER 

1. An artificial leather for automotive interior materials, comprising a back layer (10), a pore layer (20), an adhesive layer (30), and a skin layer (40) laminated in order from bottom to top, wherein a thickness ratio of the back layer (10) to the pore layer (20) is 1.5 to 3:1, the pore layer (20) is composed of a non-porous portion (21) positioned at a lower portion thereof and a porous portion (22) positioned at an upper portion thereof, and an area of 70% or more of the pore layer (20) has a thickness ratio of the non-porous portion (21) to the porous portion (22) of 0.5 to 1.5:1 when a vertical line is drawn from an arbitrary point of an upper end of the pore layer (20) through the lowest point of a pore located at the lowermost position among pores present in the porous portion (22).
 2. The artificial leather according to claim 1, wherein a thickness ratio of the back layer (10) to the pore layer (20) is 1.6 to 2.9:1.
 3. The artificial leather according to claim 1, wherein a thickness ratio of the non-porous portion (21) to the porous portion (22) is 0.6 to 1.4:1.
 4. The artificial leather according to claim 1, wherein the artificial leather has an elongation of 80 to 180% in a length direction and an elongation of 110 to 290% in a width direction.
 5. The artificial leather according to claim 1, wherein the artificial leather has an elongation of 90 to 170% in a length direction and an elongation of 120 to 280% in a width direction.
 6. The artificial leather according to claim 1, wherein the artificial leather has a tensile strength of 30 to 80 kgf/30 mm in a length direction and a tensile strength of 20 to 70 kgf/30 mm in a width direction.
 7. The artificial leather according to claim 1, wherein the artificial leather has a tensile strength of 35 to 70 kgf/30 mm in a length direction and a tensile strength of 25 to 60 kgf/30 mm in a width direction.
 8. The artificial leather according to claim 1, wherein the artificial leather has a softness of 3.6 to 4.5.
 9. The artificial leather according to claim 1, wherein the artificial leather has a seam line on the back layer corresponding to a back thereof, and is used in a covering process of one or more automotive interior materials selected from the group consisting of a crash pad, a door trim, a console box, an armrest, a headrest, and a headliner.
 10. The artificial leather according to claim 1, wherein the back layer (10) is a circular knitted fabric impregnated with polyurethane.
 11. The artificial leather according to claim 1, wherein the artificial leather further comprises a surface treatment layer on a surface of the skin layer (40).
 12. A method of manufacturing an artificial leather for automotive interior materials, the method comprising: back layer formation step S1 of forming a back layer by impregnating a knitted fabric; skin layer formation step S1′ of forming a skin layer on an upper portion of a release paper; pore layer formation step S3 of forming a pore layer on an upper portion of the back layer; adhesive layer formation step S4 of forming an adhesive layer on an upper portion of the skin layer; skin layer bonding step S5 of bonding the skin layer on which the adhesive layer has been formed to an upper portion of the pore layer; and release paper removal step S7 of removing the release paper, wherein a thickness ratio of the back layer to the pore layer is 1.5 to 3:1, the pore layer is composed of a non-porous portion positioned at a lower portion thereof and a porous portion positioned at an upper portion thereof, and an area of 70% or more of the pore layer has a thickness ratio of the non-porous portion to the porous portion of 0.5 to 1.5:1 when a vertical line is drawn from an arbitrary point of an upper end of the pore layer through the lowest point of a pore located at the lowermost position among pores present in the porous portion.
 13. The method according to claim 12, wherein, in back layer formation step S1, the knitted fabric is a circular knitted fabric.
 14. The method according to claim 12, wherein skin layer formation step S1′ is a step of applying a skin layer composition onto an upper portion of a release paper and drying the release paper to form a skin layer, wherein the skin layer composition comprises 10 to 60 parts by weight of a solvent and 10 to 40 parts by weight of a pigment based on 100 parts by weight of a polyurethane resin.
 15. The method according to claim 12, wherein pore layer formation step S3 is a step of applying a pore layer composition on an upper portion of a back layer, which is the impregnated knitted fabric, and then performing coagulation in an aqueous dimethylformamide solution and rinsing to form a pore layer, wherein the pore layer composition comprises 20 to 50 parts by weight of a solvent and 0.5 to 2 parts by weight of a pore control agent based on 100 parts by weight of a polyurethane resin. 